richardson



- r 16 602- Apnl 1927' R. s. RICHARDSON Re AUTOMATIC TELEPHONE SYSTEM Original Fi ed eb-14. 191sv :s Sheets-Sheet 1 Rod r? E. FmhaEon R 16 602 Apnl 1927' R. s. RICHARDSON e AUTOMATIC TELEPHONE SYSTEM 3 Sheets-Sheet 2 Qr1g;1na1Filed Feb. 14, 1916 I Hndn B. Richardson April 19 1927.

R. e. RICHARDSON AUTOMATIC TELEPHONE SYSTEM Original Fi-led Feb. 14, 1916 a S bsets-Sheet :5

Inusn m I Each-15 ERmhaPdsnn Reieoued Apr. 19, 1921.

A UNITED STATES PATENT OFFICE.

nomr'nr armorial-insert, or cmcaeo. rumors, ASSIGNOR, BY MESNE ASSIGNMENTS,

To AUTOMATIC nnnc'rnrc Inc, or CHICAGO, rumors. A conrorwrron' or mana- WARE.

AUTOMATIC TELEPHONE SYSTEM.

Original application flled February 14, 1918, Serial No. 78,161. Renewed June 28, 1920, Serial No. 892,0, now Patent No. 1,439,124, dated December 19, 1922, Divided and application filed November 6, 1922, Serial 1T0. 589,171! Patent No. 1,482,398, dated April 29, 1924. Application for reissue filed April 21, 1926. Serial No. 103,654.-

ter the lines are divided into groups, and

there is provided for each group of lines a sufiicient number of finder switches to handie the maximum number of originating. calls from that group. Each finder may be directly connected to a selector or connector switch, depending on the size of the system, through the medium of which a calling line. when located by a finder switch, may be extended into connection with a called line.

One of the features disclosed and claimed in this application, which is a division of "my application Serial No. 78,161 filed February 14, 1916, renewed June 26, 1920, Serial No. 392,042, is an improved circuit arrangement according to which the line relay of a selector or connector swltch to which a calling line is extended is energized over .a'

of an energized relay in one switch (a finder switch) to maintain the connection until ground is applied to the release trunk conductor at the next switch in the train (selector or connector). When this occurs the locking winding is short circuited'and the energized relay in the first switch falls back.

The holding of the connection during the change over from one switch tothe next switch in the series is therefore made positive and reliable. as it is independent of the deenergizing time of a slow relay, as is the case with systems now in use.

To accomplish the foregoing and other useful ends my invention comprises means which will be hereinafter set forth and claimed, reference being had to the accompanying drawings.

In the drawings Figures 1 and 2, taken in order with the lines at the end thereof in alignment. represent diagrammatically a complete circuit connection between a callin substation A and 21 called substation A, in a system embodying the principles of my in-. vention. lished through the medium of the finder switch 0, the selector switchD, and the connector switch E. In Figure 3, I have shown a top view of the mechanism of the finder The said connection has been estabswitch C. while Figure 4 represents a cross-' 7 section of Figure 3 on the line a, b. In Figure 5, I have shown the starting connections and a portion of the banks of three finder switches belonging to the same group. Figure is a schematic representation of one of the clrcuits shown in Figure 5. The substation A (Fig. 1) may be of the general type of substation shown in British patent to T. G. Martin No. 1,419 of 1910'. As herein represented it consists of the re ceiver 2, transmitter 3, receiver hook 4,

ringer 5, and condenser'fi. Bein an automatic substation it is also provi ed with a pair of impulse springs 8 and 9 controlled by the impulse wheel 7, which in turn is con-. trolled through the medium of a finger hole dial (not shown). The impulse springs-and wheel as shown herein may be-arranged in the manner shown in British G. S. Dicker 29,654 of 1910.

The line conductors 11 and 12 of the subpatent to S.

station A. have allotted to them at the ex-' change the line and cut-ofi relays21 and a set of multiple bank contacts in the bank of each finder switch, one of these sets being indicated by reference characters 35-39, inclusive; a pair of contact springs 45 and 46 associated with each set of tinder bank contacts; and a setof multiple bank contacts (not shown) in the bank of cach connector, such as connector E (Fig. 2), which has'access to the group uf'lines of which the line of substation A is one. The normal conductors 13, 14, and 15 extend to the latter sets of bank contacts. -The functions of the line and cut-ofi' relays are very similar to the usual functions of these relays in other well known systems, although the line relay 21 in my system is somewhat difi'erent in o ration as will appear more fully hereina ter. The bank contacts 37. 38, and 39 in thebank of finder switch (3 are multipled to corresponding contacts in the banks of all other finder switches in the group; each line of the group of which the line of substation A is one, of course, being mult-ipled through the banks of these finders in the same manner. The bank contacts 35 and 36, however, and similar contacts of other lines of the group, are not multipled straight to corresponding contacts in the banks of other finders, as are contacts 37, 38, and 39, but are connected in a pcculiar loop'circuit which will be fully explained hereinafter.

The finder switch C may be briefly described as a rotary switch whose wipers have a movement in one direction only and have no normal osition. Referring to Figures 3 and 4, t 0 frame of the switch is formed of a circular base plate 200 and a ring shaped upper mounting plate 201, the two being separated the proper distance and rigidly connected by posts 202, 203, 204, and 205. Supported on hearings in the upper and lower frame plates, is a shaft 206 to which is rigidly secured an arm 207, a ratchet wheel 210. and five sets of wipers insulated from each other, one set being indicated by reference character 215. A ma'gu'ct 208, attached to base plate 200 by means of the heel piece 209, is adapted, when encrgizerl, to rotate the shaft 206 through the medium of armature 211, pawl 212, and ratchet wheel 210. The spring 212 tends to hold the pawl 212 constantly in engagement with ratchet wheel 210. The dog 214, which also engages the ratchet wheel 210 serves to prevent backward rotation of the shaft 206.

The'various sets of bank contacts are preferably arranged in a complete circle, and there are shown in Fig. 3 fifty of these sets, by which it appears that there will be fifty lines in the group to which the finder switch C has access. The exact number, however, is immaterial, it being easily possible and perhaps advisable to increase the number of lines in each group to one hundrcd. It is understood that, the manner in which the finder switch banks and wipers are shown in Figure 1 is purely diagrammatic, the actual construction of these parts being as shown in Fig. 4.- In the latter drawing thebank contacts 35-39, inclusive, correspond to the same numbered contacts in Figure 1 and are individual to a certain line. The bank contacts 40'44, inclusive, correspond to the wiper 40-44, inclusive, in Figure 1, and are preferably complete circular strips extending around the entire circumference of the bank. Attached to the strips 4044', inclusive, are conductors .which extend to the relays of the switch,

shown at C (Fig. 1). It is evident that at alltimes a certain set of contacts such as contacts 35-39, inclusive,-will be connected to the common strips 40'44', inclusive, by means of the five sets of wipers.

As before mentioned, each set of bank con-- tacts has associated with it a pair of normally closed contact springs, one of these pairs. being indicated by reference characters and 46 (Figs. 1 and 4). The arm 207' carries an insulating piece 47 which is adapted to separate the pair of contact springs between which it happens to be resting. Or, in other words, no matter what set of bank contacts the wipers are resting on, the pair of contact springs associated with that set will be separated by the insulating piece 47.

Referring now to Fig. 5, I have shown diagrammatically therein six sets of bank contacts in each of three finder switch banks, together with six starting wires and their connections in the banks. The six sets of contacts immediately adjacent to the line and cut ofi' rela s at the left of the drawing are located in t e bank of the first finder of thegroup, finder switch C; the six sets of contacts at the extreme right ofthe drawing are located in the bank of the last finder of the group (not shown) while the other six sets of bank contacts are located in the bank of an intermediate finder. It is to he understood that in actual practice there may be more than three finder switches in a group and that each finder, as already explained, will have fifty or evenone hundred sets of contacts instead of six, but it is thought that sufiicient contactsets and finder banks are represented to show what is intended. Counting "from the top the three sets of finder switch wipers are shown resting, respectively on the third. second and hfth sets of contacts in their respective banks. The wipers when in motion move in an upward direction, as represented in Fig. 5. I

The starting wires are indicated by reference character 230-235, inclusive. There are as many separate starting wires as there bank contact 250, bank contact 252, contact are lines in the group and each starting wire extends from theline relay of the line w th which it is associated to the starting WII'O .contact of that line in the bank of the first finder switch of the group. For example, starting wire 23). extends from a contact on the line relay of No. 3 line to bank contact 238. in the third set of contacts in the bank of the first finder switch. 111 the same manner. starting wire 233 extends from a contact on the line relay of line'No. 4 to-bank contact 239 in the fourth set of contacts in the bank of the first finder switch. Also, by referring to Figure 1. the starting wire 321 associated with the line of substation A is seen extending from contact 29 on line relay 21 to bank contact 36 in the bank of finder switch G, which'is assumed to be the first switch of'the group.

From the foregoing it will be clear that each line of a group is provided with an individual starting wire extending from its line relay to the bank of the first finder switch in the group. I will now explain how the various starting wires are connected in the banks of the remainingfinder switches. Considering the starting wire 230, which is the one associated with line No. 1(not shown), a complete series circuit which includes every set of contact springs such as 45 and 46 (Figs. land 4) in every finder switch may be traced as follows: starting wire 230, bank contact 236, contact springs 270 and 271, bank contact 242. bank contact 248. contact springs 272 and 273,

springs 274 and 275, bank contact 253, wire junction 300, and starting wire 231 to bank contact 237. From this point the circuit may be traced more briefly by way of the second pairs of contact. springs of the three finders in series to wire junction 301; thence by way oft-he third pairs of contact springs of the three finders in series to wire junction 302; thence byway of the fourth pairs of contact springs of the three finders in series to wire junction 303; thence by way of the fifth pairs of contact springs of the three finders in series to wire junction 304; and thence by way of the sixth pairs of contact springs of the three finders in series and the dotted conductor 310 to wire junction 305, where itjoins starting wire 230 again and forms a complete loop. Conductor 310 is shown dotted to indicate that it passes through other pairs of contact springs not shown befo e returning to wire junction 305. The individual starting wires may 'be considered as taps taken off from the main loop circuit at the fi st finder switch-bank. It

will be observed that the above described of the insulating pieces 290, 291, and 292' which correspond to insulating piece 4.7

be termed emergency starting and stop ing against their "respective springs only when instant after its energizing circuit is broken.

(Figs. 1 and 4). The finder switches may be considered as each standing, when idle,

at the division point between two adjacent sections, each finder being adapted to serve those lines whose startin on to the section imme: iately in front of that finder. There maybe but one starting wire attached to a given section or there may be many more, depending obviously on" the position of the other findcrs.

For the sake of additional clearness I have shown in Figure 6, the loop circuit and si g starting wires of Fig.5. together with a starting relay in each of the three finders, all unnecessary details being omitted. V hen taken in connection with the forego ing description of Fig. 5, it isthought that Fig. 6 will be understood without difficulty.

The relays shown at H (Fig. 5) are common to a group of finder switches and may relavs. Their functions will be more ully explained hereinafter. Returning now to Figure 1, the finder switch C is connected directly with the selector switch I) which may be of the gcneral type of selector switch disclosed in U'. S. Letters Patent No. 815,321,

granted March 13. 1906, to Keith. Erickson and Erickson: being, however, of the particular type disclosed in British patent to the.

Automatic Telephone Manufacturing Com, pany, No. 2543 of 1914. Among other details the selector. D comprises a bank of contacts arranged in horizontal rows or levels, which contacts are adapted to be engaged by a set of wipers 120. 121, and 122 carried upon a shaft (not shown) which has a vertical movement controlled by a vertical magnet 109, and a rotary movement controlled by a rotary magnet 110. The operation of the various parts of the switch 'is controlled through the medium of the double wound line relay 100. Means for permitting the switch to.be rcstored to normal position is provided in the release magnet 105 which, upon energizing, withdraws the retaining pawls from the shaft. The contacts 112 and 113 make the shaft has been'raised one or more steps from its normal position. The relays 104 and 106 are slow acting, i. e. each of these relays is able to retain its armature for an As is well known, a selector of the type shown herein may be given access to a number of groups of connector switches, which connectors in turn have access to groups of subscribers" lines for the purpose of completing-connections thereto. One of these connectors is shown a E, Fig. 2. The connector Emay be of the generaltype of connector switch disclosed in U. S. Letters Patent No. A

815,176 granted March 13, 1906, to Keith, Erickson and Erickson; being, however, of

wires are tapped the particular type disclosed in British atcnt to the Automatic Telephone Manu acturing Compan No. 2270 of 1914. Among other details t e connector E comprises a bank of contacts arranged in horizontal rows or levels. which contacts are adapted to be engaged by a set of wipers 16O, 161, and 162, carried upon a shaft (not shown) which has a vertical movement controlled by the vertical; magnet 143; and a rotary movement controlled by the rotary magnet-144. The usual side switch comprising the wipers 156, 157, 158, and 159 is controlled by the private magnet 147 in the well known manner.

is provided in the release magnet 152, which,

upon energizing, withdraws the retaining pawls from the shaft and restores the side switch wipers to their first position. The contacts 154 and 155 make contact with their respective springs onlywhen the shaft has been raised one or more steps from its normal position. The relays 153 and 146 are slow acting.

The connector E has access through its wipers and bank contacts toagroup of subscribers stations one of which is shown at -A. The substation A may be similar in ,all respects to substation A and is provided with similar individual line equipment.

For supplying current for operating and talking purposes I have shown a battery B having one terminal grounded. The battery B shown in Fig. may be the same battery or a different battery from that illustrated at B in Fig. 2. For supplying ringing current I have shown a generator R and for busy signaling purposes I have shown a. busy signaling machine Q .llaving given a general description of the apparatus I will now proceed to describe the operation of a system embodying the principles of my invention. For the purposes of this explanation it will be assumed that the subscriber at substation A (Fig. 1) desires to establish a connection with thesubscriber at "substation A (Fig. 2). Inasmuch as a great deal of the automatic apparatus shown herein is old and well known in the art, having been fully described in the publications referred to, its operation will be described in a more or less general manner, the details being given only when they have to do in some way with the application of the principles of my invention.

The 5 operation of the various parts ofthe switch Means end of the stroke, the or' Referring now to Fig.' 1, the subscriber at substation A, upon removing his receiver to initiate the call, completes a circuit which includes a winding of line relay 21, indi-' vidual starting wires 321, and a. pair of start- 54, winding of relay 53, contact 70, armature '69, contact 68, spring (37, wiper 41, bank contact 36, starting wire 321, contact 29, s ring 30, contact 27, armature 26, line com actor 11, to and through substation A, line conductor 12, armature 24, contact 25, and winding 22 of line-relay 21 to battery B. In response to. current flow in the above path, inlays 21, 53, and 54 attract their armatures. The armature of relay 21 is adjusted with a rather long stroke and the contact against spring 32 is made'before spring is separated from contact 29. As a result of the latter operation, which takes place near the inal energizing circuit is broken, but not fore relays 53 and 54 have full attracted their armatures. Relay 21 is enab ed to complete its stroke by reason of the new ath to ground by way of common rela 90 c osed by armature 28 and spring 30. temporary locking circuit for relay 54 may now be traced as follows: ground at G winding 55 of relay 54, contact 66, spring 63, wiper 42, bank contact 37, spring 32, armature 31, holding winding 23 of line relay 21, and winding of cut oil relay 20 to battery B. The cut off relay 20, upon energizing, breaks the energizing circuit of winding 22 of line relay 21, but relay 21 retains its armature attracted by reason of its holding winding 23, now carrying current in series with the cut oil relay winding.

An instant after the temporary locking circuit 'of relay 54 is established by the energization of relay 21, the slow acting relay 53 retracts its armature, thereby completmg an energizing circuit. for line switchmg relay 51 as follows ground at G, armature 78, contact 80, armature 74, contact 75, holding winding 56 of relay 54, armature 81, contact 82, and winding of relay 51 to battery B. Relay 51., upon attracting :its armatures, brings about the following circuit changes. By bringing armature 64 into engagement with spring 63 and by separating the latter fromcontact 66, the temporary locking circuit of relay 54 by way of its winding 55 is broken and relay 54 remains energized by reason 'of its low resistance holding windin 56. By the substitution of windin 56 far winding 55, the test contact 37 an its multiples are brought suf- Ill] . ficiently hear to ground potential to make the line of substation A busy to otherfinder switches that may be started. Also, by reason of the low resistance of holding winding 23 of line relay 21, the conductor and the multiple test contacts in the tends are brought snfliciently near to ground tential to make the line of substation A Eiisy to "those connector switches. As a further result of the energization of relay 51 the wiper 41 is disconnected from relay 53, mid is connected directly to wiper in an obvious manner; This is done for the pur of maintaining the continuity of the starting circuit while finder switch 0 is busy. Finally, by bringing armatures 59 and 60 into engagement, respectivel with contacts 61 and 62, relay 51 exten s the lineconductors 11 and 12 to the double wound line relay 100 of the selector D. Two energizin circuits for relay 100 may now be trace one ofwhich extends over the following path: ground at G, winding 103 of relay 100, contact springs 115 and 116, contact 61, armature 59, wiper 43, bank contact 38, conductor 16, line conductor 12,

substation A, line conductor 11,'conductor 17, bank contact 39, wiper 44, armature 60, contact 62, contact springs 117 and 118, and winding 102 of relay-100 to battery B. The second energizing circuit extends as follows: ground at G, armature 78, contact 80, armature 74,contact 75, armature 60, contact 62, contact springs 117 and 118, and winding 102 of relay 100 to battery B. Ordinarily the latter circuit, which is in eifect a short circuit of winding 103 and the substation A, could {1e dispensed with. Its puIr-posewill appear ater.

V pon attract ng its armature, the line relay 100 completes an energizing circuit for the slow acting relay 104, which relay, upon "energizing, prepares circuits for the vertical and rotary magnets 109 and 110 in the well known manner and also com letes a. hold ng circuit which ma be trac over the following path: groun at G and contactv springs 130 and 131 to armature 64,

- where the circuit divides, one branch extending by way of the winding of line switching relay 51 to battery B, and the other branchextending by way of spring 63, wiper 42, bank contact 37, spring 32, armature 31,- winding 23 of relay 21, and windingof cut off relay 20 to battery B. It willbe observed that as soon as the above holding circuit is established the winding 56 of relay 54 is short circuited. Upon deenergizing, relay 54 breaks the last described energizing circuit of line relay 100,

thereb leaving the selector D under the control o the substation A.

The purpose of the auxiliary energizing banks of connectorswitches to which it ex-' circuit for line relay 100 ma now be Should the subscriber at su ation'A remove his receiver and replace it, in the interval between the pulling up of relay 21 and. the pulling up of relay 104 of the selector, rela 54 would remain locked up by its win ing 56, thereby maintaining the finder switch in a busy condition until the next call by substation A. The auxiliary cner izing circuit for line relay 100 is provided to obviate this possibility. It may also be pointed out at this time that in case the upper talkin conductor or the release trunkconductor o' 'the trunk lineextending from the finder switch 0 to the selector D is open, then the holding circuit which is normally established by relay 104 cannottbe completed, and relay 54 of the finder 0 remains locked up. If the upper talking conductor is open relays and 104 cannot be energized andif the release trunk conductor is open, although relays 100 and 104 are energized the energization of the latter is not effective to complete the holding circuit, due to the 0 en condition. Relay 54, therefore, is not s ort circuited and remains locked up, as stated, through its left hand winding, which supplies current to relay: 51, 21, and 20. Thus if the trunk line is open the finder C is maintained in connection with the calling line even after the subscriber at substation A hangs up his receiver, and this condition continues until a switchboard attendant notices the trouble and corrects it. I

Before continuing with the operation of the selector D and connector E it will be well to consider the operation in the case where no finder switch is restin upon the contacts of the calling vline.

that its wipers happen to, be nearer to the contacts of the line of substation A than the wipers: of any otherfinder. It follows then that the section of the starting loop to which starting wire 321 is tapped will terminate in the bank contact upon which wiper 41 is resting, as explained in connection with Fig. 5.

' Upon the removal of the' receiver at substation A an energizing circuit is completed as previously described for relays 21, 53, and 54, except that in this case the circuit includes a. portion of the starting loop.

e will assume that the finder switch C isidle and Relay 21, upon energizing, pr'epares'a circontact 29 and spring 30, and

tains its armature for an instant thereby com leting the :following circuit: ground at G armature 78, contact 79, armature 76 contact 77, winding of relay 52, winding of rotary magnet 50, interrupter contact springs 58, and common relay 91 to battery B. Relay 52, upon attracting its armature 72 completes the above circuit over a path which is independent of the relay 53, whereby the deenergization of this relay an instant later is without effect.

As soon as the circuit just described is completed the rotary magnet 50 operates to .vibrate its armature 211 bymeans of the interrupter contact springs 58, thereby ro-.

' 37 an energizing circuit is completed for relay 54 and eut-ofif relay 20 over the followingpath: ground at G, winding 550i relay 54, contact 66, spring 63, wiper 42, bank contact 37, spring 32, armature 31, winding 23 of role 21, and winding of cut-off relay 20 to attery B. The above circuit is the same as one previously described and referred to as the temporary locking circuit of relay 54. Upon attracting. its armature,

relay 54 breaks the rotary magnet circuit by separating armature 78 and contact 79, thereby stopping the rotation and bringing the wipers 4044, inclusive to rest upon contacts 35-39, inclusive. F rom this point the operation is the same as described in the case where it was assumed that the wipers of finder switch C were already resting upon thecontacts of the line of substation A.

We ma now. return to the selector D and consider riefiy its operation. In response to the manipulation of the dial at substation A in accordance with the first digit of the desired number, the impulse wheel 7 in-. terrupts the circuit of the line relay 100 a number of times in the well known manner. As a result of these interruptions the line rela 100 is deenergized a corres onding number of times, sending an impu se at each deenergization from ground at G to the slow acting relay 106 and the vertical magnet 109 in series. The vertical magnet, in response to these impulses, steps up the shaft until the wipers stand opposite the horizontal level in which are located contacts which are terminals of the desired group of connectors. The relay 106, being slow acting, retains its armature during the series of impulses and closes a circuit for the test relay 108 which latter relay pre ares a circuit for the rotary magnet and ocks itself to round at G. At the end of the series of impulses the relay 106 deenergizes, thereby closing a circuit for the rotary magnet 110, whereupon the wipers 122 start rotatin insearch of a trunkfextending to an idle connector. As is well known, the rotary magnetinterrupts itsown circuit and also the locking circuit of the test rela at every energization, the contacts in the attercircuit, however, being short 120, 121, and I circuited by the test wiper 121 while passing over busy or grounded contacts. As soon, therefore, as the test wiper reaches an ungrounded test contact the test relay falls back and opens the rotary magnet circuit, thereby bringing the wipers to rest upon contacts which are terminals of a trunkleading to an idle connector switch, assumed in this case to be the connector E. As a further result of the deenergization of the test relay 108, a circuit is completed for the line switching relay 107, which relay, upon energizing, disconnects the extended line conductors 12 and 11 from the windings of the line relay,

100 and further extends them by way of wipers 120 and 122 and bank contacts 123 and 125, to the double wound line relay 140 of the connector E.

The line relay 140 thereupon energizes over the previously traced circuit through substation A, and completes an energizing circuit for slow acting relay 153. Relay 153, upon energizing, prepares a circuit for the vertical and rotary magnets 143 and 144 and also completes a new holding circuit as fol lows: ground at G, contact springs 170 and 171, bank contact 124, and wiper 121 to wire junction 132, where the circuit divides, one

branch extendin by way of contact springs 133 and 134 and winding of line switching relay 107 to battery B, while the other branch extends by way otcontaet 112 andin this case in deenergizations of the'line re- 'lay 140 of the connector E. At each deener ization the line relay 1'40 sends an im-' pu se fromground at (i to the slow acting .contaet 111. to wire junction 135, where it e relay 146 and the vertical magnet 143 in series, side switch wiper 156 being in its first position. The vertical magnet, in response to these impulses, steps up the shaft until the wipers stand opposite the horizontal level in which are located contacts which are ter- Ininals of the line of substation A. The

relay 146 being slow acting, retains its armature during a series of impulses and maintams a circult irom ground at G to the private'magnet' 147 At the end ofthe series to advance them to their second position. The subscriber at substation may now operate his dial in accordance with the third v and final digit of the desired number, resultpoint, a circuit is completed from ground at ing as before in deenergizations of the line relay 140. In this case, however, the line relay sends im ulses to the slow acting relay 146 and. t e rotary magnet 144, side switch wiper 156 being in its second position. The rotary magnet operatesin response to these impulses to rotate the wipers 160, 161, and 162 until they rest, respectively, upon contacts 163, 164; and 165, these station A. 7 v

As side switch wiper 157 comes into enment with its third position contact G by way of wiper 161, bank contact 164,

'ble wound answering and winding of cut-ofi relay 20' to battery B. The cut-01f relay 20, upon energizing,

disconnects the line conductors of substation- A from their connections at the line- Y relay 21'.

multiples of contact 164 in the banks of other connectors of the group, thereby mak-'- Ground at (5: also extends to in the line of substation A busy, to other ca ls. Y 1

By the engagement of side switch wipers 158 and 159 with their third position contact points the line conductors 11 and 12 are extended to 'the wipers 160 and .162, respectively, thereby completing the connection between the two substations. By the engagement of side switch wiper 156 with its third position contact point, a circuit is completed for the ringing relay 149 in series with the interrupter 1, whereby ringing current is pro'ected intermittently out over the line of su station A to signal the called subscriber.

The subscriber at substation A has now established the required connection with substation A', and the bell at the latter substation is being rung to attract the attention of the subscriber. substation A removes his receiver from the hook a circuit is com leted for the douridge rela 150, which relay serves to supply talking atteiy to the transmitter at substation A. Relay 150, upon energizing, compietes a circuit for the rin cut oil relay 148, which relay locks up and breaks the circuit of the ringing relay 149, thereby stopping the ringing. As a further result of the energization of relay 150, the incoming line conductors are reversed as regards theirconnection with the windings of line relay 140. This operation iswithout importance in the system shown \Vhen the subscriber a't' herein, although it isprovided in case a is desired to operate meters or similar apparatus.

The calling and the called subscriber may I now converse without further effort, the voice currents taking the path shown by the heavy lines. 1

Upon the'completion of the conversation the subscribers willahangup their receivers. By the replacement of the receiver at substation A the circuit of line relay 140 is broken. Upon deenergizing relay 140 breaks the circuit of slow acting relay 153. Upon the deenergization of relay 153, the connector E is restored to normal in the regular manner, and as a furtherresult, ground is remQvedfrom the. holding; circuit contacts being terminals of the line of sub-Q f switch 0. The selector D is then restored to normal following the deenergization of relay 107, and line switching relay 51 ofthe finder switch C, line relay 21, and cut-.ofi relay 20 are deenergized, whereupon all the apparatus will have been restored tonormal position. It should be mentioned that the line switching relay 51 is made sli htly slow acting to insure that spring 63 wifi not make against contact 66 until after armature 31 of the line relay leaves spring 32 The reason for this adjustment is obvious.

The operation of a connector such as the connector E when the called line is busy-is well known and has been fully described in the ublications referred to. My invention -1nvo ves notlnng new in connection with spectively, with a common locking wire extending to all the line relays of the group of lines, and a common battery supply wire extending to the rotary magnets of all the finder switches of the group. -The relays 92 and 93 are normally ener ized and are controlled, respectively, by he relays 91 and 90.

From the previous description of the op eration of finder switch C, it will be clear that the line relay of a calling line is locked up by way of common locking conductor and relay 90 during the time a finder switch is rotating to find that line. Since the ro-' tary magnets of all the finder switches of the grou are in series with relay 91, it follows hat in the ordinary operation of the system whenever relay is energized relay 91 will be energized also.

Assume now that two subscribers whose starting wires happen to be tapped on to the same section of the starting loop remove their receivers at the same instant. It is evident that but one finder switch will be started. This finder will stop at whichever line it reaches first, whereupon relay 91 will deenergize, but relay 90 will remain energized since the second calling subscriber still has his line relay locked up. Relay 91, being slow acting, will pull up its armatures when the first lmpulse of current passes through it in series with the rotary magnet and retains its armattlres until the finder switch comes to rest on. the contacts of the callin v line. The ungrounded pole of battery l is now connected to conductor by way of back contact of relay 93 and back contact of relay 91. Conductor 95 is joined to the starting loop at some convenient oint and afi'ords means for start-, iug auot ier finder switch to locate the second calling line.

\Ve will assume now that a subscriber removes his receiver and thereby starts a switch banks. When, therefore, the finder which was started arrives at the contacts of the line in question, its test wiper finds no battery potential and the finder switch is unable to stop, but will continue to rotate indefinitely. 1 provide, however, a conductor indicated by reference character 96 which at this time will have battery potential upon it. by Wu of back contacts of relays 90 and 92. gonductor 96 is joined to one or more multi le vtest contacts in. the

finder banks and a ords means for stopping a rotating finder switch when there is no calling line waiting to be served.

it will be seen from the foregoing that I have provided a very eflicient method of starting finder switches ima system of the general type described, by which the movement of'thc finders is reduced to a minimum; and it will be seen further that. l have provided certain new and advantageous circuit arrangements for accomplishmg the foregoing and other beneficial results, thereby tending. to increase the general serviceabilityof a tinder switch system. While I have described in the foregoing certain specific embodiments of my invention, I do not wish to be held strictly to the forms shown herein, for various adaptation will no doubt suggest themselves to persons skilled in the art. I desire, therelay independent of the ca fore, to include and have by Let switch, a finder switch operable or extend ing said line into connection with the controlling relay of said switch to com lete a circuit therefor, said controlling re ay remaining deenergized until the line is found, and means in said finder switch responsive to the finding of said line for completing a prelnninar energizingcircuit for said controlling re ay.

2. In a te ephone system, a line, an auto matic switch, a controlling role for said switch, a finder switch operable or extending said line into connection with the controlling relay of said switch to complete a circuit therefor, means in said finder switch for completing a second circuit for said controllin relay, andimeans under the control ofusaic relay for breaking said second circu1 3; In a telephone system, an automatic in said bridged switch, a trunk line terminatin switch, a, hne relay in said switc across the said trunk line, means for connecting a calling line with said trunk line,

means effective when the connection is established for automatically completing a local circuit for said relay over a talking condoctor of said trunk to energize the said relay independent of the calling line, and means for opening said local circuit after a predetermined time interval.

4. In a tele hone system, an automatic switch, a trun line terminatin in said switch, a line relay in said switc i bridged,

across the said trunk line, means for extending a calling line to said trunk line, means for automatically completing a local circuit for said relay over a talking conductor of said trunk to energize the said reling line, and means operated responsive to the closure of said local circuit for opening said local circuit.

5. In a telephone system, a trunk line, an automatic switch in which said trunk terminates, means for extending a calling line to said trunk, a relay connected to said trunk and adapted to be energized over the two sides of the calling line in, series, means actuated when the calling line is extended to said trunk for automatically closing a local circuit for said relay including a talking conductor of said trunk, and means controlled by said relay for opening said local scriber controlled automatic switch for ex tcndin a connection from said calling line to sai called line, means responsive to an initiation of a call by a subscriber on said calling line for connecting said calling line and said switch together whereby said switch is placed under the control of said switch controlling device. and means at the exchange for closing a shunt around said switch controlling device for an interval after the connection is established.

7. In a telephone system, a calling line trunk lines, an automatic switch controllc over the calling line to connect the same with an idle trunk line, a locking circuit for retainin said switch in operated position establis ed when the line and trunk are connected, and means ogilerated automatically and independent of t e calling line for opening said locking circuit.

8. In a telephone system, a calling line, trunk lines, an automatic switch controlled overthe calling line to connect thesame with an idle trunk line, a locking circuit for retaining said switch in operated position established when the line and trunk are connected, a rela connected to each trunk, means for closing a local energizing circuit for the relay associated with the trunk in use, and means controlled by said relay for openingsaid locking circuit.

9. In a telephone system, a trunk line terminating in an automatic switch, a line relay in said switch bridged-across the talking conductors of said'trunk line in series with the exchange battery, a second switch for connecting a calling line with said trunk line, and means in said second switch for automatically connecting one of the talking conductors of said trunk line to ground to energize said line relay independent of the callin line.

10. a telephone system, a trunk line, terminating in an automatic switch, a line relay in said switch bridged across the talking conductors of said trunk line in series with the exchange battery, a second switch for connecting a calling line with said trunk line, and means in said second switch for groundin one of the talking conductors of saidtrun line and for maintaining said conductor grounded for an interval after the connection is established, whereby the placing of the said line relay under the control of the calling line is automatically dela ed.-

11. In a telephone system, a trunk' ine, terminatin in antautomatic switch, a line relay in said switch bridged across the talking conductors of said trunk line in series with the exchange battery, a scond switch for connecting a calling. line with said trunk line, a local circuit for said line relay including one conductor of said trunk line, and .means in said second switch for maintaining said localcircuit closed for an interval after the connection is established.

In an automatic telephone system, two serially related automatic switches for use 111 connecting a calling and a called line, a trunk hne extending between said switches a release trunk conductor included in sai trunk line, means in the first switchfor gronndlng said conductor, means in the secend switch for grounding said conductor thereafter, and means in saidfirst switch responsive to the 'groundin of said conductor in the second switch or removing the ground in the first switch.

13. In a telephone system, two serially related automatic switches for use in connecting a calling and called line, a trunk line extending between said switches, said trunk line including a release trunk conductor, a self locking relay in the first of said switches having a lockin winding through which a holding ground is supplied to said conductor, and means for rounding said conductor in the second of sai switches, whereupon the said locking winding is short circuited and the relay is deenergized to open its locking circuit.

14. In a telephone system, a subscribers line, two serially related automatic trunking switches for extending said line when callmg, a trunk line extending between said switches, said trunk line including a release trunk conductor, a cut-off relay for said line, a holdin circuit for said relay including said con uctor, a locking rela in the first oi! said switches havin a 100 ing winding through which a holting ground is supplied to said conductor to maintain the cutoff relay ener ized, and means for groundin said CODL uctor at the'se'cond of said switches, whereupon said locking winding is short circuited and the said locking relay is deenergized to interruptits locking cir- I cuit.

15. In a telephone system, a line, two serially related automatic switches for extending said line when calling, a cut-ofi relay for said line, a self locking relay in the first of said switches, a circuit for said cut-ofi relay including the locking winding of said looking relay, and a relay in the second of said swltches for shunting said locking winding by lcompleting said circuit over a different at P 16. In a telephone system, a line, a trunk line, an automatic switch for connecting said line and trunk line, a switching relay in said switch fonclosing the connection, a release trunk conductor over which said switching relay is maintained energized, a relay in said switch having a locking winding through which a battery potential is applied to said conductor, and means in said trunk line operative after the connection is established for placing substantially the same battery potential on said conductor whereby said locking relay is shunted and deenergized. i

'17. Ina telephone system, a train of antomatic serially related switches for connecting a calling and :1. called line, a release trunk conductor for maintaining said switches in operated position, a relay in one switch having a locking windin for supplying ground to a section of said conductor for an interval during the setting 1180f the connection, and a rela in a succee ing switch for directly groun ing said conductor to short circuit and deenergize said first relay.

18. In a telephone s stem, two serially related automatic switc es for setting up a connection, a switching relay in the first switch for closing the talking circuit at said switch, a second relay in said switch having an energizing winding and a lockingwinding, means for closing a temporary circuit through the energizing winding, a circuit for said switching rela contacts of said second relay an its lockin winding, and a relay in said second switch for shunting said locking winding.

19. In a telephone system, an incoming line, a plurality of outgoing lines, automatic switching mechanism for interconnecting said incoming line with any of said outgoing lines, a holding circuit completed when said incomin line is connected to one of said outgoing lines, means in sai d holding circuit for temporarily bringing together the two sides of a seized outgo ng circuit, means responsive to said operation for initiating the release of said seized outgoing circuit, and other means normally eflectiv'e to prevent said releasing operation.

20. In a telephone system, an inco ining line, a'plurality of out oing lines, a switch for interconnecting-sai incoming line with one of said outgoing lines, an impulse relay connectedto one si e of the connected outgoing line, a holding circuit for said switch established when the connection between the incoming and outgoing lines is completed, a slow releasing rela in said holding circuit, means controlle by said slow releas ing relay for closing the operating circuit of said impulse relay independent of said incoming line, means responsive to the operation of said impulse relay for initiating the release of said outgoin line, and other means includin a secon ener izing circuit for said impu se relay extending through said incoming line for preventing said re leasin operation. 7 a

21. n a telephonesystem, a calling line trunklines, an automatic switch controlled over the calling line to connect the same with an idle trunk line, me'ans operatin automatically and independently of the cal including ing line to initiate the release of the connected trunk line, and means normally con line for preventing trolled over the calling such releasi 0 operation.

22. In a i elephoue system, a calling line trunk lines, an automatic switch controlle over the calling line to connect the same with an idle trunk line, means for temporaril holding said connection independent of t e calling line, means operating automatically to disable said holding means to break the connection, and means normally efiective to prevent the breaking of the connection in case the calling subscriber continues with the call.

23. In a telephone system, a calling line, trunk lines, an automatic switch controlled over the calling line to connect the same with an idle trunk line, means for temporarily holding said connection independent of the callin line, means for transferring the control or the holding means to the calling line in case the calling subscriber continues with the call, and meanso erated automaticall for disabling said olding means to re ease the connection in case the calling subscriber hangs up his receiver before the control of the holding means is transferred.

24. In a telephone system, a trunk line terminatin in an automatic switch, means for operating said. switch controlled by a calling subscriber over the two sides of said trunk line in series, a second switch for con-' a calling line with said trunk line means associated with the trunk line for c osing a holding circuit for the connecting means 1n-' eluding said release trunk, and means for locking the connecting means to prevent disconnection of the line and trunk line in case the holding circuit is not established.

26. In a telephone system, two serially related switches operable successivel to set up a connection, a trunk line exten ing between said switches, means in the second switch effective to prevent the release of the first switch in case the trunk line is in order, and means in the first switch eflectiveto prevent its release in case thetrunk line is out of order.

27. In a telephone system, a trunk line, means including an automatic switch for connectin a callin line with said trunkvline, a r ay in sai switch for preventing moon v r 11 .the release thereof, and means for locking calling line, and means 'for transferring the said relay energized in case the said trunk control of said releasing means to the cull- 1" line is open. a in line in case said trunk line is in working 28'. In a telephone system, a trunk line, or or when connected with. a

5 an automatic switch for connecting a call-. Signed by me at Chicago, Illinois, this ing line with said trunk line, releasing means 16th day of April, 1926.

for said switch, local means for controlling v said releasing means independent of the RODNEY G. RICHARDSON. 

